| 摘要: |
| 采用离子螯合反应、水化热测试及电阻率测试等，研究了2膦酸基丁烷1,2,4三羧酸(PBTCA)、羟基亚乙基叉二膦酸(HEDP)和二乙烯三胺五亚甲基叉膦酸(DTPMPA)这3种有机膦酸对水泥浆水化硬化特征的影响，并探讨了其影响机理．结果表明：有机膦酸对Ca2+具有很强的螯合作用，其中的单分子膦酸基团数量越多，对金属离子的螯合值越大，由强到弱依次为DTPMPA、HEDP、PBTCA；相同掺量条件下，有机膦酸的缓凝效力远大于葡萄糖酸钠，其对水泥浆的水化抑制能力随着膦羧基团数量的增大而增大；有机膦酸优先与Ca2+、Mg2+等形成稳定的螯合物，限制了Ca2+、Mg2+等参与水化产物的形成，延长了水化溶解期与诱导期；与空白样不同，有机膦酸的掺入使得水泥水化加速期的电阻率微分曲线上未出现1对波峰波谷，另外，电阻率微分曲线拐点与水泥浆凝结时间密切相关；适当掺量的有机膦酸对水泥28d抗压强度和抗折强度具有增强作用，但过量有机膦酸会导致水泥强度显著下降. |
| 关键词: 水泥浆 水泥水化 有机膦酸 螯合反应 电阻率 缓凝机理 |
| DOI：103969/j.issn1007 9629202002002 |
| 分类号: |
| 基金项目:江西省交通运输厅科技项目（2017C0003 3）；国家自然科学基金资助项目（51608239）；交通运输部公路科学研究所基本科研业务专项基金资助项目（2018 E0003）；广西科技计划项目（桂科AC16380105） |
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| Influence of Organic Phosphonic Acid on Cement Hydration Characteristics at Early Age |
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LI Lihui1, TIAN Bo1, HAN Gensheng2, ZHAO Wenli3, QUAN Lei1
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1.Research Institute of Highway Ministry of Transport, Beijing 100088, China;2.Jiangxi Provincial Expressway Investment Group Co., Ltd., Nanchang 330025, China;3.Beijing Construction Engineering Group New Building Materials Co., Ltd., Beijing 100021, China
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| Abstract: |
| The effects of 2 phosphonic butane 1,2,4 tricarboxylic acid(PBTCA), hydroxyethyl diphosphonic acid(HEDP) and diethylenetriamine pentamethyl phosphonic acid(DTPMPA) on the hydration and hardening characteristics of cement paste were studied by ion chelation reaction and measurement of hydration heat and resistivity. The mechanism of it was discussed. The results show that the organic phosphonic acid has drastic chelation effect on calcium ion. The more the single molecule phosphonic acid groups, the greater the chelating value of metal ions, the order of strength from strong to weak are successively DTPMPA, HEDP and PBTCA. The retardation efficiency of the organic phosphonic acid at the same dosage is much higher than that of sodium gluconate, and its inhibition ability against hydration of cement slurry increases with the increase of the number of phosphine carboxyl groups. Organic phosphonic acid preferentially forms stable chelates with calcium and magnesium plasma, which restricts participation of calcium and magnesium plasma in the formation of hydration products, and extends the hydration dissolution and induction period, related to the number of phosphonic groups. Phosphonic acid makes the resistivity differential curve of the hydration accelerated period to show that a pair of peaks and troughs disapear, to be different from the control sample. In addition, the inflexion point of resistivity differential curve is closely related to cement slurry setting time. Appropriate amount of the above organic phosphonic acid has an enhanced effect on the compressive strength and flexural strength of cement 28d, but an excessive amount leads to a significant decrease in strength. |
| Key words: cement paste cement hydration organic phosphonic acid chelation reaction electrical resistivity retarding mechanism |
